The present invention relates, in general, to the shaping and forming of biological tissue for providing an implant for restoration of the structure and/or function of an anatomical member and, in particular, to a synthetic tympanic membrane, an associated malleus or ossicular substitute and method of making the same.
Over the past 20 years many methods and tissues have been used to repair tympanic membrane perforations. These efforts have generally utilized a scaffolding of autogenous connective tissue from various sources. The surface of epithelial covering has been derived from a free or pedicled skin graft or from epithelium migration from the host's external auditory canal skin. Dried (and, hence, nonviable) temporalis fascia in combination with epithelial migration from adjacent canal skin has been the most successful of this type of repair. Closure of the perforation is virtually assured with this technique but lateral displacement of the graft and blunting of the anterior sulcus has resulted in thick tympanic membranes in a small but significant percentage of cases. This undesirable effect frequently results in unsatisfactory hearing improvement when it occurs.
When, in addition, restoration of one or more of the ossicles is required, in particular, the malleus, some additional surgical difficulty is encountered. This is due to the lack of any provision in the conventional use of fascia tissue for preattaching a malleus or functionally similar member or for attachment of a host malleus to the tissue during surgery.
In addition, fascia tissue grafts do not ordinarily assume the conical shape of a natural tympanic membrane. This is undesirable in that the normal conical shape of the natural tympanic membrane is believed to be advantageous for better hearing.
More recently, the closure of tympanic membrane perforations and the reconstruction of ossicles with fresh sterile homograft tympanic membranes and ossicles has been attempted with varying degrees of success. In each case, temporal bone cores are taken at the time of an autopsy and dissected. The preparation of homograft tympanic membranes with or without the malleus and other ossicles involves delicate, time-consuming and expensive procedures which are wholly dependent on the availability of suitable donors.
The ready availability of an inexpensive synthetic tympanic membrane with or without one or more of the ossicles or functionally similar member and having the physical shape and characteristics of a homograft tympanic membrane is, therefore, highly desirable as is the availability of synthetic members for reconstructing other parts of the auditory system.